Telephone-exchange system.



C. WHITE. TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED MAR. 22. ISIS.

Patented Dec. 17, 1918.

//7 van/0r Char/es W/v/fe y UNI D STATES CHARLES WHITE, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK N. Y., A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented Dec. 17, 1918.

Application filed March 8, 1918. Serial No. 221,167.

To all whom 2'25 may concern Be it known that I, CHARLns WHITE, a citizen of the United States, residing at East. Orange, in the county of Essex, State of New Jersey, have invented certain neW and useful Improvements in Telephone-EX- change Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems and more particularly to such systems in which trunk circuits are employed.

he object of this invention is to reduce the number of circuits required between different switchboards or operators positions. by utilizing the same circuit for various classes of service.

In accordance with one feature of this invention, a trunk circuit adapted for reciprocal operation between two stations and terminating in a plurality of connecting terminals at each station, each such terminal being adapted for use with a particular class of service, is provided with means whereby the trunk circuit may be selectively isolated for a particular class of service by the association of a suitable connecting circuit with the proper connecting terminal at either station during the initiation of a call over a trunk.

In accordance with another feature of this invention, the trunk circuit is provided with means whereby the class of service desired over the trunk is indicated at either station during the initiation of the call from the other station and the use of the proper connecting circuit and switching terminal is assured.

These and other features not specifically mentioned above will more clearly appear from the following specification and the an ncxed drawing, in which is shown diagrammatically, a trunk circuit embodying the invention, together with sufficient portions of suitable connecting circuits for the difierent classes of service to properly illustrate the invention.

In the drawings, the switchboards, operators positions or stations A and B are joined by the trunk circuit E, terminating at position A in jacks 2 and 13, and at position B in jacks 102 and 113. Associated with acks 2 and 13 are calling signal lamps 11 and 17 respectively, and associated with jacks 102 and 113 are calling signal lamps 111 and 117, respectively. Jacks 2 and 102 D are provided for use with jacks 2 and 13, V

respectively, and at station B similar connecting circuits, F and G, are provided for use with acks 102 and 113, respectively, only sufficient of each connecting circuit being shown to properly illustrate the invention.

It is believed that the invention may be more fully understood from the following description of the operation of the system shown on the drawing.

Assuming that it is desired to extend a local connection from station A to station E, the operator at station A inserts the calling plug 1 of cord circuit C in the jack 2 of the trunk E. Lamp 3 is lighted by means of a circuit established from battery through lamp 3, normal contact of relay 1, sleeve contacts of plug 1 and jack 2, lower normal contact of relay 5, lower normal contact of relay 6 and lower winding of relay 7 to ground. Relay 7 thereupon operates, establishing a circuit extending from battery through lower alternate contact of relay 7, upper normal contactof relay 8, lower normal contact of relay 9, to one conductor of the trunk, and due to the reversal of the conductors thereof, the upper normal contact of relay 109, winding of relay 110 and tip normal contact of jack 102 to ground. Relay 110 thereupon operates and causes the lighting of calling lamp 111 over a circuit from battery through contact of relay 110, normal contact of relay 107 and lamp 111 to ground. A circuit also extends from the contact of relay 110 through the winding of relay 108, to ground and relay 108 therefore operates. Relay 108 by opening its lower normal contact interrupts the normal sleeve circuit of jack 113, by closing its lower alternate contact impresses a busy test potential on such sleeve, and by closing its upper alternate contact shunts condenser 120 and thereby provides a path for the fiow of the direct current required for supervisory purposes. The busy test potential is connected to the sleeve of jack 113 over a path extending from battery through resistance 11 1 and lower alternate contact of relay 108 to the sleeve contact of jack 113. Upon the insertion of plug 1 in jack2 a circuit is also es- 7 not lighted since relay tablished from ba tery through windin of relay 18, sleeve contacts of plug 1 and ack 2, lower normal contact of relay 5, lower normal contact of relay 6 and lower winding of relay 7 to ground. Relay 18 operates, and connects battery and ground to the ring and tip respectively, of plug 1 through the windings of repeating coil 19.

The operator at station E obseiwing the illumination of calling signal lamp 111 inserts plug 101 of cord circuit F, which is similar to cord circuit C in the jack 102, thereby opening the normal contacts of jack 102 and establishinga circuit from battery through winding of relay 118, sleeve con-- tacts of plug 101 and jack 102, lower normal contact of relay 105, lower nonnal contact of relay 106 and lower winding of relay 107 to ground. Relay 10'? operates, eX- tinguishing calling lamp 111, and relay 118 also operates, connecting battery and ground to the ring and tip, respectii 'ely, of plug 101 through the windings of repeating coil 119. Relays 10 and 101 are thereby immediately operated over a circuit established from battery through a winding of repeating coil 119, lower contact of relay 118, winding of relay 101, ring contacts of plug 101 and jack 102, upper alternate contact of relay 108, lower normal contact of relay 109, one conductor of the trunk circuit and due to the reversal of the trunk conductors, the upper normal contact of relay 9, winding of relay 10, tip contacts of jack 2 and plug 1, upper contact of relay 18 and a *inding of repeating coil 19 of cord circuit C to ground. Due tothe immediate operation'ot relay 101- the lighting of lamp 103 is prevented, while the operation of relay 10 causes the operation of relay 8 over a circuit from battery through the contact ofrelay 10 and winding of relay 8 to ground. However, lamp 11 is 7 is operated. 11elay 8 by closing its upper alternate contact establishes a shunt around condenser 20, by opening it lower normal contact interrupts the normal sleere circuit 01 jack 13 through relay 9 to ground, and by closing its lower alternate contact connects a busy test poential to such sleeve over a path from battery through resistance 1sand lower alterpate contact of relay 8 to sleeve of jack 18. Lamp 3 is also extinguished by the operation of supervisory relay elover a circuit established from battery through a windmg of repeating coil 19, lower contact or" relay 18, winding of relay 1, ring contacts or plug 1 and jack 2, upper alternate contact of relay 8, lower normal Contact of relay 9, one conductor of the trunk, upper normal contact of relay 109, winding of relay 110, tip contacts'of jack 102 and plug 101, up-

er contact of relay 118 and a winding of repeating coil 119 to ground. A talking circuit thereupon completed over the conductors of the trunk so that a subscriber whose line is associated with cord circuit C may converse with another subscriber whose line is associated with cord circuit F.

Upon the disconnection of either cord circuit, the supervisory lamp in the cord circuit connected with the other end of the trunk will be lighted in the usual manner to give a disconnect signal and when both cord circuits are disconnected from the trunk all apparatus returns to its normal condition.

Assuming that the operator at station A desires to extend a toll call to station E, the operator at station A inserts plug 21 of cord circuit 1) in jack 13 of trunk E, establishing a circuit from battery through resistance 22, sleeve contacts of plug 21 and jack 18, lower normal contact of relay 8 and winding of relay 9 to ground. Relay 9 is thereby operated, disconnecting the tip and ring conductors leading to jack 2 from the trunk conductors and connecting thereto in a transposed n1anner,the tip and ring conductors leading to jack 13. By the closure of its lowest alternate contact, relay 9 also completes a c rcuit from battery through winding of relay 5 and lowest alternate contact of relay 9, to ground. Relay 5 operates, opening at its lower normal contact the normal sleeve circuit of jack 2 and impresses a busy test potential on the sleeve of such jack over a path from battery through resistance 11 and lower alternate contact of relay 5 to the sleeve of jack 2. The operator at station A then operates ringing key 24 thereby ringing in the usual manner over the trunk and causing the operation of relay 115 over a circuit extending from the source of ringing current through lower alternate contact of key 21, ring contacts of plug 21 and jack 13, uppermost alternate contact of relay 9, one conductor of the trunk, and y reason of the reversal of the trunk conductors, the lower normal contact of relay 109, condenser 120, normal ring contact of jack 102, condenser 116 and winding of alternating current relay 115 to ground. Relay 115, operating, causes the lighting of calling lamp 117 over a circuit from battery through the contact of relay 115 and lamp 11'? to ground. A second circuit is also established from battery through the contact of relay 115, winding of relay 106 and upper normal contact of relay 105 to ground. Relay 106 is thereupon operated and locked up by means of a circuit from battery through the upper alternate contact and winding of relay 106 and the upper normal contact of relay 105 to ground. Current is also supplied over a circuit from battery through the upper alternate contact of relay 106 and the lamp 117, to ground, for the purpose of maintaining lamp 117 in a lighted condition after the cessation of the rin ing current through relay 115. The normal sleeve circuit of jack 102 is interrupted by the opening of the normal contact of relay 106 and a busy test potential is placed upon such sleeve over a path from battery through resistance 1141, lower alternate contact of relay 106 and lower normal contact of relay 105 to sleeve of jack 102. The operator at station B, observing the illumination of lamp 117, inserts plug 121 of cord circuit G, which circuit is similar to cord circuit D, in jack 113. Relay 109 is operated over a circuit from battery through resistance 122, sleeve contacts or plug 121 and jack 113, lower normal. contact of relay 10S and Winding of relay 109 to ground. The operation of relay 109 disconnects the tip and ring conductors leading to jack 102 from the trunk conductors and connects thereto, in a transposed manner, the tip and ring conductors leading to jack 113. The closure of the lowest alternate contact of relay 109 causes the operation of relay 105 over a circuit from battery through winding of relay 105 and lowest alternate contact of relay 109 to ground. Relay 106 is thereupon released and lamp 117 is thereby extinguished. However, the busy test potential is maintained on the sleeve of jack 102 over a path extending from battery through resistance 11-1 and alternate contact of relay 105 to the sleeve of jack 102, and the normal sleeve circuit of jack 102 is also maintained in an interrupted condition by the opening of the lower normal contact of relay 105.

As in the former case a talking circuit is thereupon completed over the conductors of the trunk so that a subscriber whose line is associated with cord circuit D may converse with another subscriber whose line is associated with cord circuit G. Upon the completion of the conversation, the operator at station A may actuate the ringing key 24, thereby sending ringing current over the ring contacts of plug 21 and jack 13, uppermost alternate contact of relay 9, over one conductor of the trunk'circuit, middle alternate contact oi' relay 109, tip contacts of jack 113 and plug 121, upper normal contact of key 124, a winding of repeating coil 126, winding of relay 125, a second winding of repeating coil 126, lower normal contact of key 124, ring contacts of plug 121 and jack 113, uppermost alternate contact of relay 109, over the other conductor of the trunk, middle alternate contact of relay 9, tip contacts of jack 13 and plug 21 and upper alternate contact of key 24 to ground. Relay 125 thereupon operates, causing the supervisory lamp 123 to be lighted over a circuit from battery through lamp 123 and contact of relay 125 to ground, thereby giving a disconnect signal t the operator at station 13. Similarly, the operator at station B may originate the disconnect signal by actuating ringing key 12%, sending ringing current over a similar circuit including windings of repeating coil 26 and relay 25, thereby causing the operation of relay 25 and the subsequent lighting of lamp to give aoperator at station A. Upon the disconnection of the cord circuits at both stations all apparatus returns to its normal condition.

It will be noted that in the first assumed case it would be impossible to answer the call at station E with cord circuit G in connection with jack 113, even by disregarding the busy test potential impressed on the sleeve of such jack, since the sleeve circuit of jack 113 is open and therefore relay 109 can not be operated. Also it would be impossible to effectively associate the cord circuit G with. jack 102 since battery and ground are not connected to the tip and ring conductors as required for operating the supervisory apparatus.

It would be impossible to answer a call, of the nature of that secondly described, with cord circuit F in connection with ack 102 even by disregarding the busy test potential impressed on the sleeve of such jack, since the sleeve circuit is open and therefore relay 11S cannot operate and the tip and ring conductors of the cord circuit F are not closed. It would also be impossible to answer a call with cord circuit F in connection with jack 113 since relays 118 and 109 will not operate when connected in series. For the reasons just stated, it would be impossible'to originate a call with cord circuit C in connection with jack 13 and due to the absence of battery and ground connections for such cord circuit, it would also be impossible to orginate a call by means of cord circuit D in connection with jack 2.

Although in both or the above mentioned cases the calls have been described as having been originated by the operator at station A it will be noted that such calls may he originated by the operator at station B, following the same method of operation as described.

It will thus be seen that by means of this invention a single trunk circuit between two stations may be employed in a reciprocal manner in connection with difi'erent classes of service and that such trunk circuit may be positively isolated for a particular class of service by the use of a suitable connecting circuit inconnection with a particular connecting terminal of the trunk circuit in originating the call over the trunk.

What is claimed is:

1. In a telephone exchange system, a plural service trunk connecting two stations, a connecting terminal therefor at each station for each class of service. and means operative upon the initiation of the call through any disconnect signal to the one of the terminals to isolate the trunk for the associated selected service.

in a telephone exchange system, a plural service trunk connecting two stations and terminating at each station in a connecting terminal for each class of service, a link circuit at each station for each class of service,

and means for selectively isolating the trunk for a particular class of service in initiating a call by the connection of a link circuit for such service with the corresponding terminal at one station.

3. in a telephone exchange system, a plural service trunk for reciprocal operation be tween two stations, a connecting terminal therefor at each station for initiating or answering calls for each class of service, a link circuit at each station, means operative upon the initiation of a call through one of the terminals at either station to isolate the trunk for the associated service, and means cooperating therewith to indicate the link circuit to be used in answering the call at the other station.

a. In a telephone exchange system, aplural service trunk for reciprocal operation between two stations, a connecting terminal therel' r at each station adapted for initiating or answering calls for each class or". service, a link circuit at each station for each class of service, a plurality of relays operative upon the initiation of a call through one or the terminals at either station to isolate the trunt for the associated service, and a. s 'naling device operating simultaneously therewith to indicate the link circuit to he used in answering the call at the other station.

5. In a telephone exchange system, a trunk circuit for reciprocal operation between two stations, a normally connected and a normally disconnected switching terminal therefor at each station, a link circuit each station adapted for connection with each switching terminal thereat, means operative upon the connection of the proper link circuit with the normally connected switching terminal at one station to display a calling signal associated with a normally connected terminal the other station, and means cooperating therewith to prevent the contemporaneous connection with a trunk of either normally disconnected switching terminal.

6. In telephone exchange system, a trunk circuit for reciprocal operation between two stations and terminating at each station in a normally connected and a normally disconnected switching terminal, each of said ter n inals having testing contacts, a link circuit at each station adapted for connection-with each switching terminal thereat, means operative upon the connection of the suitable link circuit with the normally connected terminal at one station to display a calling signalassociatedwith the no ally connected terminal at the other station, and means coo iierating therewith to impress abusy test potential upon the testing contacts of the normally disconnected terminal at the other station and to positively prevent the contemporaneous connection of either normally disconected terminal with the trunk.

7. In a telephone exchange system, a trunk circuit for reciprocal operation between two stations, a normally connected and normally disconnect-ed switching terminal there for at each station, a link circuit at each station adapted for connection with each switching terminal thereat, means operative upon the com ection oif suitable link circuit with the normally disconnected terminal at either station to connect such terminal with the trunk and to disconnect therefrom the normally connected ter 'nal at that station, means operative during such connection to display a calll in signal associated with the normally disconnected terminal at the other station, and means operative upon the connection of the corresponding link circuit with the normally disconnected terminal at the other station to connect such terminal with the trunk and to disconnect therefrom the normally connected terminal at that station.

8. In a telephone exchange system, a trunk circuit for reciprocal operation between two stations and terminating at each station in a normally connected switching terminal and a normally disconnected switching terminal, both having testing contacts; a link circuit at each station adapted for connection with each switching terminal thereat; means operative upon the connection of a suitable link circuit with a normally disconnected terminal at either station to con- 7 nect such terminal with the trunk, to disconnect therefrom the normally connected terminal at that station. and to impress a busy test potential on the testing contacts thereof; and means operative upon the initiation of a call over the trunk to impress a busy test potential upon the testing contacts of the normally connected terminal at the other station. 7

' 9. In a telephone exchange system, a dual service trunk connecting two stations and terminating at each station in a connecting terminal for each class of service, a link cir cuit at each station adapted for connection with each oi the terminals thereat, and means controlled by the association of one of said link circuits'with a corresponding terminal at one end of the trunk to determine the character of link circuit to be connected with the other end of the trunk.

10. In a telephone exchange system, a

dual service trunk ci cuit for reciprocal operation between two stations, a connecting terminal and. a calling signaling device therefor for each class of service at each station, a link circuit at each station adapted for use with each class of service, means operative trunk from either station by means of a link circuit for either class connected to the corresponding terminal thereat to operate the calling signaling device at the other station, and means cooperating with said means to permit the effective association of a similar link circuit with the trunk at the other station and to prevent the contemporaneous effective association of a dissimilar link circuit thereat.

11. in a telephone exchange system, a dual service trunk circuit for reciprocal operation between two stations, a connecting terminal and a calling signaling device therefor for each class of service at each station, a link circuit at each station adapted for use at each class of service, means operative in initiating a call over the trunk from either station by means of a link circuit of either class connected to the corresponding terminal thereat to operate the corresponding calling signaling device at the other station, and means cooperating with said means to permit the effective association of a similar link circuit with the trunk through the corresponding terminal at the other station and to prevent the effective association of either link circuit thereat with the trunk through the other terminal thereat.

12. In a telephone exchange system, a dual service trunk circuit for reciprocal operation between two stations, a connecting terminal and a calling signaling device therefor at each station for each class of service, a link circuit at each station adapted for use at each class of service, means operative during the initiation of a call Copies of this patent in initiating a call over the may be obtained for five cents each, by addressing the over the trunk from either station by means of a link circuit of either class connected to the corresponding terminal thereat to operate the corresponding calling signaling device at the other station, and means cooperating with said means to impress a busy test potential on the terminal for the other class of service at each station.

13. In a telephone exchange system, a dual service trunk circuit for reciprocal operation between two stations, a jack having a normally grounded sleeve circuit for the trunk at each station for each class of service, a cord circuit at each station adapted for use with each jack, and means operative during the initiation of a call over the trunk-from either station by means of a cord circuit connected with a corresponding jack thereat to interrupt the normal sleeve circuit of the jack for the other class of service at the other station and to impress a busy test potential on the sleeve of such jack.

14. In a telephone exchange system, a trunk circuit for reciprocal operation between two stations and terminating at each station in a normally connected and a normally disconnected terminal, a first link circuit at each station adapted for connection with the normally connected terminal, a second link circuit at each station adapted for connection with the normally disconnected terminal and switching means adapted to connect either normally disconnected terminal with the trunk, said means being inoperable when one of said first link circuits is connected with the normally con nected jack at either station.

In witness whereof, I hereunto subscribe by name this 21st day of February, A. D.,

CHARLES WHITE.

Commissioner of Patents,

Washington, D. G. 

